Amplification of cellular oncogenes occurs frequently in several human cancers and is an important mechanism of increased gene expression in solid tumors. Identification of amplified genes in tumor cells has proven to be a useful approach for understanding genetic alterations in cancer. Previous procedures for isolating probes from amplified DNA sequences have relied on tissue culture cells limiting the range of tumors which can be studied and raising questions of in vitro artifact. We have circumvented these problems by combining in gel renaturation of amplified sequences with the polymerase chain reaction. Using this approach, a novel DNA amplification unit from biopsies of human malignant fibrous histiocytoma has been identified and partially cloned. This amplification unit is derived from chromosome 12q13-14, a site commonly involved in rearrangements in soft tissue tumors, and contains at least one transcribed region (designated SAS for sarcoma amplified sequence). Proposed studies are intended to characterize the SAS amplification unit in detail at the genetic level in order to identify all genes within it which are expressed in cells carrying SAS amplification. This will be accomplished using genomic analysis techniques based on yeast artificial chromosome (YAC) cloning. A YAC contig will be established for the SAS amplification unit which will be used to map this region in sarcomas. Using probes derived from genes within the YAC clones, cDNAs for expressed genes will be isolated and characterized. This information will provide a basis for the functional analysis of the role of SAS amplification in sarcoma oncogenesis.